I arrive for my interview with Mia Wasikowska 45 minutes early, barrelling into the hotel corridor as she leaps gawkily, girlishly through a door. We lock eyes, I recognise her, she smiles shyly, as if trying to remember who I am, then realises she has no idea. This 21-year-old, the highest-grossing female film star of 2010, one of Time magazine's 100 most influential people in the world, is clearly entirely unused to being recognised. Her expression shifts to friendly confusion, and she bounds off through another door.

Even when she's completely silent, stories whisper over Wasikowska's face, which explains her latest casting as Jane Eyre, a woman whose inner monologue bubbles with wit and defiance. The film opens with Eyre's stricken flight from Thornfield Hall, after a betrayal by her great love, Rochester, and the camera focuses on Wasikowska's stripped-bare face as she runs across sodden woodland, down wet paths, and lies on a rock in the hammering rain. The scene could easily veer into parody – the sort of watery, weepy cape-and-bonnet moment French and Saunders might once have sent up. But Wasikowska never teeters into histrionics, she is always completely believable.

She started reading Charlotte Brontë's novel a couple of years ago, and was so enamoured that halfway through she called her agent, asking if any adaptations were knocking about. Two months later, she was sent a script. "I was just so struck by Jane's sense of self," she says. "She doesn't compromise herself for anybody. I have a really supportive family, but she hasn't had anyone cheering her on at all." The shoot was exhausting, six days a week in a corset, "quite physical a lot of the time, and very emotional, all the time. I don't sleep very well in general, but I would be falling asleep any 10 minutes I had. In the makeup chair, I'd be," she drops her head back dramatically, "while they were trying to fix up my eyebrows."

Wasikowska says she likes to work "inside out", building a character psychologically, and that the most important direction she was ever given is "the thought really counts". Unlike the majority of actors, her characters live palpably behind her eyes. This allowed her to hold her own against the massed mushrooms and grinning cats in Tim Burton's Alice in Wonderland, an eye-popping mess of a film in which her tough, independent Alice was nonetheless triumphant. Her co-stars in her other big hit of 2010, The Kids Are All Right, were also daunting: the fearsomely experienced trio of Julianne Moore, Annette Bening and Mark Ruffalo. But as Joni, the teenage daughter of two lesbian mothers who decides to meet her biological father, she was awkward and mesmerising.

Her defining role so far has been as Sophie in the TV series In Treatment. I mention the character, and she almost jumps in her seat: "She's probably my favourite, ever." Wasikowska comes from Canberra, Australia, and, at 17, In Treatment was the first work she had ever done in the US. It was intense – Sophie is a suicidal teenage gymnast, who has been having an inappropriate relationship with her coach, and is visiting a therapist played by Gabriel Byrne. Each episode was essentially a two-hander, and her performance was remarkably subtle. One especially wrenching moment consisted simply of her hugging her therapist's wife.

"That was the most incredible initiation ever, I was on such a high the whole shoot," says Wasikowska. "I remember each time I got a new script, reading it and being like: 'Sophie tried to kill herself in the bathroom! Shit!' I got so attached to her, because I was new in the country, I didn't really know anyone, and she was like a friend.

"It's really rare as a teenager to be offered a role that actually resembles what it's like to be a teenager, because there are so many stereotypes that might be attractive to watch, but make you think: who is that? Who has that life at 16? I don't know anybody who's like the popular girl in school. The hot chick." She wasn't? "Unfortunately not," she laughs. "I was a bit of a loner as a teenager. I never went to a single social event, because they terrified me."

Her portrayal of Sophie was partly informed by Wasikowska's own childhood experiences as an aspiring ballet dancer. The daughter of artist parents – her mother a photographer, her father a photographer and art lecturer – Wasikowska always knew she would do something creative, but wasn't quite sure what. The household was filled with activity; her mother bringing photography books home, her parents discussing their shows or the layout of their work. There were regular trips to art galleries, and she came to love the work of photographers Lee Friedlander, Roger Ballen, William Eggleston, Mary Ellen Mark, "and a thousand others who I'm blanking on". She remembers, as a kid, watching a Czech film of Alice in Wonderland, "a stop-motion version by Jan Svankmajer, and being completely disturbed and riveted".

Wasikowska's mother Marzena does a lot of portraiture, and some of her earliest memories are of having her picture taken, "waking up in the middle of the night, because a flash went off. I was like," she mimes shielding her eyes, and adopts the low growl of a Muppet, "'Mom, what are you doing!'"

Her mother was born in Poland, and when she landed a commission to work there for a year, she took the family with her. Wasikowska was eight, and there are pictures of her striding seriously through a grassy field, and looking beadily thoughtful in a jacket with a big, shiny hood that resembles a space helmet. "Our entire lives have been documented by photography, and I guess that was the beginning of acting, in a subtle way, because we never had to perform or smile for the camera, we'd just do our thing, and she'd take pictures of us. But you're definitely always aware, if you're having your photo taken, and that becomes a dynamic and a rhythm between two people."

Wasikowska has her mother's surname, as do her two siblings; older sister Jess, younger brother Kai. She says she doesn't know why, but when I ask if her mother's a feminist, she replies, "Well, yeah," in a tone that implies, "Well, duh". "I would hope everyone would be a feminist," she continues. "Feminism is just about equality, really, and there's so much stuff attached to the word, when it's actually so simple. I don't know why it's always so bogged down."

Around the time she left Poland Wasikowska began pursuing ballet seriously. "It snowballed really quickly, and I got very into it, and I was doing about 35 hours a week." She loved the way dancing made her feel: "It's such an amazing liberation. It's a contradiction, because dancing itself is so liberating, and you feel fantastic. It's like a drug. You get really high. But then the industry side of it is so rigorous, and quite oppressive, and that started to feel," she pauses, "eurgh."

She has said in the past that, when she was dancing, she was probably half her current size, "and more unhappy with my body than I am now". She tells me the pressure that came with ballet was enormous. "You'd spend 35 hours a week staring at yourself in the mirror, and start to really fixate on things that, I guess, if you have a proper perspective, are not that big of a deal." Like what? "Oh, things you only really see if you're in that world; the curve of your ankle, how big your wrist is. Ridiculous things, but when you're a dancer, they're serious." A fat wrist could ruin your career? "Yeah! It could."

I ask what she thought of the film Black Swan, with its portrayal of ballet dancers as driven, neurotic, anxious. "I thought it was pretty good," she says. "You do get very caught up in that world, and there's a lot of negativity. Actors get so pampered, and there are a lot of rewards, and dancers work just as hard, if not more so, and there's 1% of the amount of help. You work yourself to the bone."

In her case, quite literally. At 14, Wasikowska developed a spur – a painful, calcified mass on the back of her heel. She had to stop ballet for two weeks, and during that time she decided, quite suddenly, never to go back. She had been watching a lot of films that intrigued her, including Kieslowski's Three Colours trilogy, and Australian films such as Shine, My Brilliant Career and Picnic at Hanging Rock. "Ballet had been so much about achieving physical perfection, and what I liked about film was that it was the opposite …" Not exactly, I say, with a laugh. Wasikowska must be the only young woman in Hollywood who finds the place laidback when it comes to body image. "Well," she says, "it's funny, because I feel like the dance world was so hardcore in terms of image and body, and physicality, and I know that a lot of people find the film world similar, but I've found it so much more chilled out that I'm like 'meh! Whatever! Try experiencing prima ballerina land – it's crazy."

Most 14-year-olds would have taken things easy at this point, but Wasikowska has an almost unnerving, inexplicable drive. "I was always anxious to do something, I always thought – I need to do more," she holds her hands dramatically to her face and throat, her pose recalling ageing diva Norma Desmond in Sunset Boulevard. "I always felt like it was too late, and I was doomed. I think even with acting I thought: I'm far too old." She laughs shyly.

Wasikowska had always hated drama class at school, "because it felt like getting up and making a fool of yourself. It was for the loud, outgoing kids, and I definitely wasn't socially outgoing. But I don't think acting is really about that. I think there's a common misconception that the loud kid in class is the actor, and I don't find that necessarily." Where some people take to acting to draw attention to themselves, Wasikowska seems much more interested in disappearing into a role.

So with no experience whatsoever, she began ringing agents; out of a list of 12, one finally agreed to take her on. Wasn't she nervous about calling them? She cocks her head. "I think I felt less nervous than I would at a school dance. It's terrifying, to be at a school dance, or a social, or anything like that. But calling an agency, there was a level of comfort, I guess, in dealing with adults and pretending to be a professional. I was a different person when I was in that element. I wasn't like," she puts on a mock-serious voice, and thrusts a forefinger into the air, "'I am now an actor.' I was just going to try it for a certain amount of time, and if it didn't work, I really didn't want to be a struggling actor, so I wasn't going to pursue it."

She quickly began securing roles in Australian films, and within a few years she was working in Los Angeles on In Treatment. Since then, her career has built at an incredible rate; last year, she was second only to Leonardo DiCaprio on the Forbes list of the highest-grossing actors in the world ("a fluke!" she says), and she has films coming up with directors Gus van Sant and Jim Jarmusch.

One of the aspects of acting she loves most is that she doesn't always feel like, "a very articulate person, and with acting you've just got perfect words. I mean, not always, because often really good dialogue is about the miscommunication between two people. But as an actor you've been given the words, and you can immerse yourself in that perfect language and just let it wash over you, which is really quite nice."

Yet I suspect, on some level, she'd still rather be an observer, than observed. I ask whether losing her anonymity would bother her, and she says: "If it was the Twilight level of fame, where you can't go for a walk, that would be really difficult … I would not find it comfortable to be followed, or to feel like people were always aware of who you are, or had preconceived notions about you." In the interests of observation, she has followed her mother into photography, with more prodigious success; a photo she took of Jane Eyre co-star Jamie Bell, and director Cary Fukunaga, the two suspended quirkily in mid-air, was a finalist in a national portrait prize in Australia this year. She's only really been taking photographs since her acting career took off, training her camera on those pointing back at her. Many of her photos are taken on film sets, she says, because: "it equals everything out. It's become my shield and my weapon. They're always poking measuring tapes in our faces, and cameras, so I just think: I'll do the same back."